Search

CN-121983388-A - Conductive paste for solar cell, preparation method of conductive paste and solar cell

CN121983388ACN 121983388 ACN121983388 ACN 121983388ACN-121983388-A

Abstract

The application provides a conductive paste for a solar cell, a preparation method of the conductive paste and the solar cell. The preparation method of the conductive paste comprises the steps of providing conductive particles, wherein the conductive particles comprise copper cores, dense silver layers covering the copper cores, loose middle silver layers covering the dense silver layers, reinforced outer silver layers covering the loose middle silver layers, the silver grain size of the loose middle silver layers is larger than that of the reinforced outer silver layers, providing glass powder and an organic carrier, and mixing and stirring the conductive particles, the glass powder and the organic carrier to obtain the conductive paste. According to the application, the dense silver layer, the loose middle silver layer and the reinforced outer silver layer are mutually matched, so that the binding force of conductive particles and a silicon wafer is improved, the mobility of silver ions is reduced, the reliability of the solar cell is improved, and the service life of the solar cell is prolonged.

Inventors

  • ZHOU YINGYING
  • HE LIANG
  • WU PENG
  • YU WANGWANG
  • SUN MENGQI
  • SONG CHONGFA

Assignees

  • 山东润马光能科技有限公司
  • 润马光能科技(金华)有限公司

Dates

Publication Date
20260505
Application Date
20260320

Claims (10)

  1. 1. A method of preparing a conductive paste for a solar cell, the method comprising: Providing conductive particles, wherein the conductive particles comprise a copper core, a compact silver layer covering the copper core, a loose middle silver layer covering the compact silver layer, and a reinforced outer silver layer covering the loose middle silver layer, and the silver grain size of the loose middle silver layer is larger than that of the reinforced outer silver layer; Providing glass powder and an organic carrier; mixing and stirring the conductive particles, the glass frit and the organic carrier to obtain a conductive paste.
  2. 2. The method of preparing a conductive paste according to claim 1, wherein the step of providing conductive particles comprises: providing a copper core; preparing the compact silver layer covering the copper core by adopting an atomic layer deposition process; preparing a loose middle silver layer covering the compact silver layer by adopting an electroless plating process; and preparing a reinforced outer silver layer covering the loose middle silver layer by adopting an electroless plating process.
  3. 3. The method of preparing a conductive paste according to claim 2, wherein an atomic layer deposition process for preparing the dense silver layer satisfies at least one of the following conditions: The silver source comprises dimethylaminosilver; the carrier gas comprises nitrogen, and the flow rate of the carrier gas is 80 sccm-120 sccm; The reducing gas comprises hydrogen, and the flow rate of the reducing gas is 40 sccm-60 sccm; The deposition temperature is 180-220 ℃; the deposition period is 4-6.
  4. 4. The method of preparing a conductive paste according to claim 2, wherein the step of preparing the loose intermediate silver layer comprises: providing formaldehyde-EDTA reducing solution, wherein the pH of the formaldehyde-EDTA reducing solution is 9.5-10.5; Placing the copper core covered with the dense silver layer in the formaldehyde-EDTA reducing solution to form the loose intermediate silver layer; The chemical plating process for preparing the loose middle silver layer has a first soaking temperature and a first soaking time, wherein the first soaking temperature is 35-45 ℃, and the first soaking time is 1.5-2.5 h.
  5. 5. The method of preparing a conductive paste according to claim 4, wherein the step of preparing the reinforced external silver layer comprises: Adjusting the pH of the formaldehyde-EDTA reduction solution to 8-9; adding silver nitrate to the formaldehyde-EDTA reduction solution, wherein the concentration of the silver nitrate is 0.05 mol/L-0.15 mol/L; Placing the copper core covered with the loose intermediate silver layer in the formaldehyde-EDTA reducing solution to form the reinforced outer silver layer; The chemical plating process for preparing the reinforced outer silver layer has a second soaking temperature and a second soaking time, wherein the second soaking temperature is 55-65 ℃, and the second soaking time is 0.5-1.5 h.
  6. 6. The method of preparing a conductive paste according to claim 1, wherein the glass frit comprises SiO 2 、B 2 O 3 、Al 2 O 3 ; Wherein the molar ratio of the SiO 2 to the B 2 O 3 to the Al 2 O 3 is (5 to 7): 2 to 4): 0.5 to 1.5; and/or the softening point of the glass powder is 625-675 ℃.
  7. 7. The method for preparing a conductive paste according to claim 1, wherein the material of the organic carrier comprises ethylcellulose, terpineol, a leveling agent, fumed silica; The mass ratio of the ethyl cellulose to the terpineol to the leveling agent to the gas phase SiO 2 in the organic carrier is (2% -3%), the mass ratio of the ethyl cellulose to the terpineol to the gas phase SiO 2 in the organic carrier is (40% -50%), the mass ratio of the ethyl cellulose to the terpineol to the gas phase SiO 2 in the organic carrier is (0.5% -1%), and the mass ratio of the ethyl cellulose to the gas phase SiO 2 in the organic carrier is (0.2% -0.4%).
  8. 8. A conductive paste for a solar cell, characterized in that the conductive paste is obtained by the method for preparing the conductive paste according to any one of claims 1 to 7.
  9. 9. The conductive paste according to claim 8, wherein the copper core has a radial dimension of 3 μm to 8 μm; and/or the thickness of the compact silver layer is 5 nm-10 nm; And/or the thickness of the loose middle silver layer is 100 nm-200 nm; And/or the thickness of the reinforced outer silver layer is 280-500 nm; And/or the total thickness of the compact silver layer, the loose middle silver layer and the reinforced outer silver layer is 400-800 nm; and/or, the dense silver layer has a porosity of <1%; and/or the silver grain size of the loose middle silver layer is 100 nm-200 nm; And/or the silver grain size of the reinforced outer silver layer is 50 nm-100 nm.
  10. 10. A solar cell, characterized in that the solar cell comprises a substrate, a conductive paste according to any one of claims 8-9 for forming a conductive layer provided on the substrate.

Description

Conductive paste for solar cell, preparation method of conductive paste and solar cell Technical Field The application belongs to the technical field of solar cells, and particularly relates to a conductive paste for a solar cell, a preparation method of the conductive paste and the solar cell. Background In solar cells, silver-coated copper paste is often used as conductive paste to prepare conductive grid lines, so that current conduction is realized. However, the binding force between the silver-coated copper paste and the silicon wafer in the related technology is low, and the mobility of silver ions is high, so that the reliability of the solar cell is low, and the service life is short. Disclosure of Invention In view of this, a first aspect of the present application provides a method for preparing a conductive paste for a solar cell, the method comprising: Providing conductive particles, wherein the conductive particles comprise a copper core, a dense silver layer covering the copper core, a loose middle silver layer covering the dense silver layer, and a reinforced outer silver layer covering the loose middle silver layer; Providing glass powder and an organic carrier; mixing and stirring the conductive particles, the glass frit and the organic carrier to obtain a conductive paste. Wherein, in the step of providing conductive particles, the method comprises: providing a copper core; preparing the compact silver layer covering the copper core by adopting an atomic layer deposition process; preparing a loose middle silver layer covering the compact silver layer by adopting an electroless plating process; and preparing a reinforced outer silver layer covering the loose middle silver layer by adopting an electroless plating process. Wherein an atomic layer deposition process for preparing the dense silver layer satisfies at least one of the following conditions: The silver source comprises dimethylaminosilver; the carrier gas comprises nitrogen, and the flow rate of the carrier gas is 80 sccm-120 sccm; The reducing gas comprises hydrogen, and the flow rate of the reducing gas is 40 sccm-60 sccm; The deposition temperature is 180-220 ℃; the deposition period is 4-6. Wherein, in the step of preparing the loose intermediate silver layer, the method comprises the following steps: providing formaldehyde-EDTA reducing solution, wherein the pH of the formaldehyde-EDTA reducing solution is 9.5-10.5; Placing the copper core covered with the dense silver layer in the formaldehyde-EDTA reducing solution to form the loose intermediate silver layer; The chemical plating process for preparing the loose middle silver layer has a first soaking temperature and a first soaking time, wherein the first soaking temperature is 35-45 ℃, and the first soaking time is 1.5-2.5 h. Wherein, in the step of preparing the reinforced outer silver layer, the method comprises the following steps: Adjusting the pH of the formaldehyde-EDTA reduction solution to 8-9; adding silver nitrate to the formaldehyde-EDTA reduction solution, wherein the concentration of the silver nitrate is 0.05 mol/L-0.15 mol/L; Placing the copper core covered with the loose intermediate silver layer in the formaldehyde-EDTA reducing solution to form the reinforced outer silver layer; The chemical plating process for preparing the reinforced outer silver layer has a second soaking temperature and a second soaking time, wherein the second soaking temperature is 55-65 ℃, and the second soaking time is 0.5-1.5 h. Wherein the glass powder material comprises SiO 2、B2O3、Al2O3; Wherein the molar ratio of the SiO 2 to the B 2O3 to the Al 2O3 is (5 to 7): 2 to 4): 0.5 to 1.5; and/or the softening point of the glass powder is 625-675 ℃. Wherein the materials of the organic carrier comprise ethyl cellulose, terpineol, a leveling agent and fumed silica; The mass ratio of the ethyl cellulose to the terpineol to the leveling agent to the gas phase SiO 2 in the organic carrier is (2% -3%), the mass ratio of the ethyl cellulose to the terpineol to the gas phase SiO 2 in the organic carrier is (40% -50%), the mass ratio of the ethyl cellulose to the terpineol to the gas phase SiO 2 in the organic carrier is (0.5% -1%), and the mass ratio of the ethyl cellulose to the gas phase SiO 2 in the organic carrier is (0.2% -0.4%). The second aspect of the application provides a conductive paste for a solar cell, which is obtained by the preparation method of the conductive paste provided by the first aspect of the application. Wherein the radial dimension of the copper core is 3-8 mu m; and/or the thickness of the compact silver layer is 5 nm-10 nm; And/or the thickness of the loose middle silver layer is 100 nm-200 nm; And/or the thickness of the reinforced outer silver layer is 280-500 nm; And/or the total thickness of the compact silver layer, the loose middle silver layer and the reinforced outer silver layer is 400-800 nm; and/or, the dense silver layer has a porosity of <1%; and/or